Cationic materials which possess antimicrobial activity have been used in oral compositions to counter oral bacteria and to prevent and treat conditions caused by bacteria in the oral cavity, such as formation of dental plaque and calculus. The formation of dental plaque and calculus and failure to stop their proliferation are the primary cause of dental caries, gingivitis, periodontal disease, and tooth loss. Dental plaque is a mixed matrix of bacteria, epithelial cells, leukocytes, macrophages and other oral exudate. Bacteria comprise approximately three-quarters of the plaque matrix. Any given sample of dental plaque could contain as many as 400 different varieties of microorganisms. This mix includes both aerobic and anaerobic bacteria, fungi, viruses and protozoa. This matrix of organisms and oral exudate continues to expand and coalesces with other plaque growths situated nearby. The bacteria synthesize levans and glucans from sucrose found in the oral cavity providing energy for the microorganisms. These glucans, levans, and microorganisms form an adhesive skeleton for the continued proliferation of plaque. Dental calculus, or tartar as it is sometimes called, is a deposit which forms on the surfaces of the teeth at the gingival margin. Mature calculus consists of an inorganic portion which is largely calcium phosphate arranged in a hydroxyapatite crystal lattice structure similar to bone, enamel and dentine. An organic portion is also present and consists of desquamated epithelial cells, leukocytes, salivary sediment, food debris and various types of microorganisms. Developing plaque can adhere most easily at relatively irregular surfaces, such as those afforded by calculus. Calculus and plaque along with behavioral and environmental factors lead to formation of dental stains, significantly affecting the aesthetic appearance of teeth. Behavioral and environmental factors that contribute to teeth staining propensity include regular use of products that contain staining chemicals or color bodies such as coffee, tea, cola or tobacco and use of stain promoting oral products, such as those containing cationic antimicrobial agents.
Among the most common of cationic antimicrobial agents known to cause tooth staining are quaternary ammonium compounds such as cetylpyridinium chloride and metal ion sources such as stannous fluoride and stannous chloride. The tooth staining potential of these cationic materials has long been documented. Among the many approaches that have been suggested to reduce and control tooth staining and to whiten teeth is by the use of bleaches or oxidants such as peroxide. Essentially, bleaches act by oxidizing color bodies and existing stains. However, bleaches added to oral care products are typically present in low concentrations due to stability and safety limits. At these low concentrations, bleaches such as peroxide, are generally ineffective to control stain and whiten teeth. Furthermore, bleaches do not functionally act to prevent acquisition of stains.
There continues to be a need for oral care products that provide enhanced overall cleaning and hygiene while also controlling tooth staining. Chemical technologies have now been identified that can effectively reduce tooth staining derived from cationic antimicrobials such as CPC. These chemical agents do not involve the use of bleaches or oxidants and significantly do not compromise the bioavailability of the cationic antimicrobials and therefore, their antimicrobial potency.